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Oogenesis is the process by which the female gametes, or eggs, are produced. It starts with the production of primary oocytes in a process called oocytogenesis, followed by the growth phase, and then meiosis. A single oocyte results in one mature egg and three polar bodies.

Spermatogenesis, on the other hand, is the process by which the male gametes, or sperm, are produced. The process starts with spermatogonia, which divide by mitosis to form primary spermatocytes. These then undergo two meiotic divisions to form four haploid spermatids, which mature into spermatozoa.

While these processes are sex-specific, they do have some things in common. Both oogenesis and spermatogenesis are forms of gametogenesis, the process of forming sex cells or gametes. They also both involve meiotic divisions, reducing chromosome numbers from diploid (2n) to haploid (n). Additionally, both processes are regulated by similar hormones (FSH and LH). Both processes also begin with a period of multiplication and growth, followed by two meiotic divisions.

The differences between oogenesis and spermatogenesis are mainly based on the quantity and quality of the gametes produced. Oogenesis produces one viable egg and three polar bodies that usually degenerate and die. This is due to the unequal division of cytoplasm during meiosis in oogenesis. In contrast, spermatogenesis results in four viable sperm cells from one spermatocyte because the division of cytoplasm is equal. Also, spermatogenesis occurs throughout a male's adult life, while oogenesis typically ceases at menopause. Moreover, in the female body, oogenesis is initiated before birth, halted and then completed (if the egg is fertilized) after puberty, whereas in males, spermatogenesis starts at puberty and continues throughout life.